# Polymer

Our original Web Component library.

Repository: https://github.com/Polymer/polymer
Canonical: https://ross.abutalabs.com/products/polymer
Homepage: https://polymer-library.polymer-project.org/
Language: HTML
License: BSD-3-Clause
License Family: permissive
Last push: 2026-04-02T03:04:41+00:00
Link (homepage): https://polymer-library.polymer-project.org/
Link (site_page): https://polymer-library.polymer-project.org/3.0/docs/quick-tour
Link (site_page): https://polymer-library.polymer-project.org/3.0/docs/install-3-0
Link (site_page): https://polymer-library.polymer-project.org/3.0/docs/first-element/intro
Link (site_page): https://polymer-library.polymer-project.org/3.0/docs/first-element/step-2

## Health v2 (maintenance only)
Score: 57/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 75, release rhythm 8, longevity 100
- inputs: {"age_days": 5123, "days_push": 153, "days_rel": 695, "gap_med": null, "n_releases_24m": 1}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 22017, forks 1959 (observed 2026-08-28T04:11:32.279915+00:00)

## What it is
Polymer is Google's original library for building encapsulated, reusable Web Components that work like standard HTML elements, with features for custom elements, Shadow DOM styling, data binding, and events. The library is now in maintenance mode, with Lit (LitElement) recommended as its successor for new development.

## Use cases
- build reusable web components
- create custom HTML elements with shadow DOM
- maintain a legacy Polymer 2.x codebase
- migrate an older Polymer app to Polymer 3.0 modules
- share UI components across frameworks via web components
- learn how web components and data binding work

## When to choose
- you maintain an existing Polymer-based application and need compatibility updates
- you want standards-based Web Components with data binding and legacy element support
- you need to incrementally migrate Polymer elements toward LitElement

## When to avoid
- you are starting a new project - use Lit (LitElement) instead
- you want a component library with a large active ecosystem and frequent updates
- you need framework features like routing or state management beyond component building

## Facets
- artifact type: library
- maturity: maintenance
- function: frontend-framework, ui-components, templating, state-management
- domain: web-development, frontend, developer-tools
- platform: browser
- tags: web-components, custom-elements, shadow-dom, data-binding, polyfills, lit-element-successor, javascript, nodejs

## Member repositories
- Polymer/polymer (main) score 57
- Polymer/old-docs-site (docs) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:32.279915+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T16:57:44.492329+00:00, confidence not recorded.
  - readme: https://github.com/Polymer/polymer (fetched 2026-08-28T04:11:32.279915+00:00, sha 0af7a30eca1e)
  - homepage: https://polymer-library.polymer-project.org/ (fetched 2026-08-29T07:56:04.501052+00:00, sha b1561606db3d)
  - site_page: https://polymer-library.polymer-project.org/3.0/docs/quick-tour (fetched 2026-08-29T07:56:04.510531+00:00, sha 24962fb8f1a4)
  - site_page: https://polymer-library.polymer-project.org/3.0/docs/install-3-0 (fetched 2026-08-29T07:56:04.513030+00:00, sha 84dc514f1bf7)
  - site_page: https://polymer-library.polymer-project.org/3.0/docs/first-element/intro (fetched 2026-08-29T07:56:04.514976+00:00, sha 4ddffa9ff93a)
  - site_page: https://polymer-library.polymer-project.org/3.0/docs/first-element/step-2 (fetched 2026-08-29T07:56:04.516884+00:00, sha 2c44ad99def2)
  - site_page: https://polymer-library.polymer-project.org/3.0/docs/first-element/step-3 (fetched 2026-08-29T07:56:04.519339+00:00, sha 4aeb9c067fc3)
  - site_page: https://polymer-library.polymer-project.org/3.0/docs/first-element/step-4 (fetched 2026-08-29T07:56:04.521724+00:00, sha 3a173b28ce64)
  - site_page: https://polymer-library.polymer-project.org/3.0/docs/first-element/step-5 (fetched 2026-08-29T07:56:04.523713+00:00, sha 0991b73c07d8)
  - site_page: https://polymer-library.polymer-project.org/3.0/docs/about_30 (fetched 2026-08-29T07:56:04.525710+00:00, sha 880d8cff516a)
- Data as of 2026-08-30T08:39:29.467469+00:00.